This invention relates to photographing apparatus and, more particularly, to a photographing apparatus for an endoscope, in which an endoscope, a photographic attachment and a light source unit are used in combination to take endoscopic pictures of a body cavity.
In endoscopic photographing of a body cavity, an endoscope, a photographic attachment and a light source unit are used in combination. Usually the endoscope and photographic attachment are assembled together as a collective unit, while the light source unit, which includes switches for setting photographing data such as exposure constants and a light source, is disposed in a separate place and is connected to the endoscope and photographic attachment through a cable. Therefore, one who observes and photographs the body cavity is likely to be remiss in the operation of the light source unit since concentrated attention has to be paid for observing the body cavity when photographing it. Particularly, where a plurality of exposure constant setting switches are provided as push button switches arranged in a row, it is likely that several switch buttons are depressed at one time by mistake because the operator usually has to look at the switches at a distance and in a somewhat unnatural direction and operate them by reaching out a hand. Also, it is sometimes likely that the operation of a switch is forgotten when photographing. If several switch buttons are depressed at one time or no switch button is depressed, a proper exposure constant cannot be obtained. In such a case, proper exposure cannot be obtained, and a picture of insufficient clarity results.
Another deficiency in the endoscopic photographing apparatus using a push button switch exposure constant setting system is that only preset exposure constants are available for stepwise selection. That is, it is impossible to obtain intermediate exposure constants.
An object of the invention, accordingly, is to provide a photographing apparatus for an endoscope, with which even an erroneous operation or failure of operation of the exposure constant setting system does not result in a substantial error of a given exposure constant, and also which permits intermediate exposure constants to be obtained.